With the recent proliferation of inexpensive, powerful computer technology, methods of communication have progressed significantly. The ordinary voice telephone call, an efficient communication technique, is now accompanied by efficient and widely used alternatives such as electronic mail and on-line chat rooms which allow participants to convey text, images and other data to each other over computer networks.
Video conferencing is another technique for communication which allows participants to convey both sound and video in real time to each other over computer networks. Video conferencing has been cost prohibitive for individuals and corporations to put into wide-spread use. Recently, however, technology has progressed such that video conferencing technology is available, at a reasonable cost, for implementation at terminals such as a desktop or portable computer or hand-held communications device.
Video-conferencing terminals are typically equipped with a video camera and a microphone for respectively capturing, in real-time, video images and sound from participants of the video-conference. The terminals also typically include a display and a speaker for playing the video images and sound in real time to the participants. When a video conference has two participants, it is called a point-to-point conference. Typically, in this arrangement, each terminal will capture video and sound from the participant stationed at the terminal and will transmit the captured video and audio streams to the other terminal. Each terminal will also play the video and audio streams received from the other terminal on the display and speakers respectively of the terminal.
When a video conference has more than two participants, it is called a multi-point videoconference. Typically, in this arrangement, each terminal will capture video and sound from the participant stationed at the terminal. Subsequently, the captured video and audio streams will be transmitted either directly or indirectly to the other terminals. Each terminal will then display one or more video streams and play the audio streams from the other participants.
A problem to confront in multi-point video-conferences concerns the large volume of video and sound data which must be processed and transmitted between the terminals. Terminals are typically coupled together over packet switched networks, such as a local area network (LAN), a wide area network (WAN) or the Internet. Packet switched networks have limited amounts of bandwidth available. The available bandwidth may quickly be exceeded by the video and audio stream data produced by participants in a multi-point video conference.
Moreover, once the video and audio streams arrive at a terminal, the terminal must process the data prior to playing it on the display and speaker. Processing multiple video streams is demanding of the terminal's processing capability. The processing capability of a terminal may quickly be exceeded by having to process more than one video stream for display. In this event, the video and audio streams may become distorted or cease to be played by the terminal.
There is a need for an automatic mechanism to control the transmission of videoconferencing data from a terminal that is participating in a video-conference. Specifically, there is a need for an automatic mechanism to reduce the transmission of high-bandwidth data when a participant at the terminal is not speaking anymore. A conventional video-conferencing program, CU-SeeMe provides a manual mechanism for starting and stopping the transmission of video data from a terminal involved in a videoconference. CU-SeeMe provides a key on the keyboard which must be depressed when a participant desires his video and audio streams to be transmitted. The participant must release the key when the participant stops speaking. During the period when key is depressed, that participant's video stream is transmitted over a network to other terminals participating in the video conference.